Commit 850103b0 authored by Claudio Imbrenda's avatar Claudio Imbrenda
Browse files

s390/mm: Warn if uv_convert_from_secure_pte() fails 



If uv_convert_from_secure_pte() fails, the page becomes unusable by the
host. The failure can only occour in case of hardware malfunction or a
serious KVM bug.

When the unusable page is reused, the system can have issues and
hang.

Print a warning to aid debugging such unlikely scenarios.

Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
parent 3ddee7e6

arch/s390/include/asm/pgtable.h

+5 −4
Original line number Diff line number Diff line
@@ -1239,7 +1239,7 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, 
	res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));

	/* At this point the reference through the mapping is still present */

	if (mm_is_protected(mm) && pte_present(res))

		uv_convert_from_secure_pte(res);

		WARN_ON_ONCE(uv_convert_from_secure_pte(res));

	return res;

}
@@ -1257,7 +1257,7 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma, 
	res = ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID));

	/* At this point the reference through the mapping is still present */

	if (mm_is_protected(vma->vm_mm) && pte_present(res))

		uv_convert_from_secure_pte(res);

		WARN_ON_ONCE(uv_convert_from_secure_pte(res));

	return res;

}
@@ -1294,9 +1294,10 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, 
	/*

	 * If something went wrong and the page could not be destroyed, or

	 * if this is not a mm teardown, the slower export is used as

	 * fallback instead.

	 * fallback instead. If even that fails, print a warning and leak

	 * the page, to avoid crashing the whole system.

	 */

	uv_convert_from_secure_pte(res);

	WARN_ON_ONCE(uv_convert_from_secure_pte(res));

	return res;

}